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Posted 2020-10-29 eric1563901725

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <algorithm>
 4 #include <cstring>
 5 using namespace std;
 6 
 7 const int maxn = 1010;
 8 int n,m,x1,y1,x2,y2,dir;
 9 int vis[maxn][maxn];
10 int pic[maxn][maxn];
11 int dix[4] = {0,1,0,-1};
12 int diy[4] = {1,0,-1,0};
13 int flag;
14 
15 void dfs(int x,int y,int turn,int dir)
16 {
17     if(flag) return;
18     if(x < 1 || x > n || y < 1 || y > m || vis[x][y])  return;
19     if(turn == 2 && x != x2 && y != y2) return;
20     if(turn > 2) return;
21     if(x == x2 && y == y2 && turn <= 2)
22     {
23         printf("YES\n");
24         flag = 1;
25         return;
26     }
27     if(pic[x][y] != 0)
28     {
29         if(x == x1 && y == y1);
30         else return;
31     }
32     vis[x][y] = 1;
33     int dx,dy;
34     for(int i = 0;i < 4;i++)
35     {
36         dx = x + dix[i];
37         dy = y + diy[i];
38         if(dir == i)
39         {
40             dfs(dx,dy,turn,i);
41         }
42         else
43         {
44             dfs(dx,dy,turn + 1,i);
45         }
46     }
47     vis[x][y] = 0;
48     return;
49 }
50 
51 int main()
52 {
53     while(scanf("%d%d",&n,&m) && n && m)
54     {
55         for(int i = 1;i <= n;i++)
56         {
57             for(int j = 1;j <= m;j++)
58             {
59                 scanf("%d",&pic[i][j]);
60             }
61         }
62         int k;
63         scanf("%d",&k);
64         while(k--)
65         {
66             scanf("%d%d%d%d",&x1,&y1,&x2,&y2);
67             if(x1 == x2 && y1 == y2)
68             {
69                 printf("NO\n");
70                 continue;
71             }
72             if(x1 < 1 || x1 > n || y1 < 1 || y1 > m || x2 < 1 || x2 > n || y2 < 1 || y2 > m)
73             {
74                 printf("NO\n");
75                 continue;
76             }
77             if(pic[x1][y1] == pic[x2][y2] && pic[x1][y1])
78             {
79                 flag = 0;
80                 memset(vis,0,sizeof(vis));
81                 for(int i = 0;i < 4;i++)
82                 {
83                     dfs(x1,y1,0,i);
84                 }
85                 if(!flag) printf("NO\n");
86             }
87             else
88             {
89                 printf("NO\n");
90             }
91         }
92     }
93     return 0;
94 }